Layer-dependent charge density wave phase transition stiffness in 1T-TaS_(2)nanoflakes evidenced by ultrafast carrier dynamics  

作　　者：Rui Wang Junbo Zhou Xinsheng Wang Liming Xie Jimin Zhao Xiaohui Qiu 

机构地区：[1]CAS Key Laboratory of Standardization and Measurement for Nanotechnology,CAS Center for Excellence in Nanoscience,National Center for.Nanoscience and Technology,Beijing 100190,China [2]Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [3]Songshan Lake Materials Laboratory,Dongguan 523808,China [4]University of Chinese Acadermy of Sciences,Beijing 100049,China

出　　处：《Nano Research》2021年第4期1162-1166,共5页纳米研究（英文版）

基　　金：We thank Prof.Yong Wang(Nankai University)for the valued discussions.We acknowledge financial support from the National Key Research and Development Program of China(Nos.2017YFA0205000,2017YFA0303600,2016YFA0200701);the National Natural Science Foundation of China(Nos.21425310,21790353,21721002,21822502,21673058);Strategic Priority Research Program of Chinese Academy of Sciences(Nos.XDB36000000,XDB30000000);the Key Research Program of Frontier Sciences of CAS(No.QYZDB-SSW-SYS031).

摘　　要：Novel physical properties emerge when the thickness of charge density wave(CDW)materials is reduced to the atomic level,owing to the significant modification of the electronic band structure and correlation effects.Here,we investigate the layer-dependent CDW phase transition and evolution of the nonequilibrium state of 1T-TaS_(2)nanoflakes using pump-probe spectroscopy.Both the low-energy single-particle and collective excitation relaxations exhibit sharp changes at〜210 K,indicating a phase transition from commensurate CDW to nearly commensurate CDW state.The single particle process reveals that the phase transition stiffness(PTS)is thickness-dependent.Moreover,a small PTS is observed in thin nanoflakes,which is attributed to the reduced thickness that increases the fluctuation and inhibits the nucleation and growth of discommensurations.In addition,the phase mode vanishes when the discommensuration network appears.Our results suggest that the carrier dynamics could be an efficient operational approach to measuring the quantum phase transition in correlated materials.

关 键 词：charge density wave 1T-TaS_(2) layer-dependent phase transition stiffness ultrafast carrier dynamics 

分 类 号：TB383[一般工业技术—材料科学与工程] O35[理学—流体力学]